The Earth and its AtmosphereThe Earth and its Atmosphere

This chapter discusses:This chapter discusses:

1.1. Gases in Earth's atmosphereGases in Earth's atmosphere

2.2. Vertical structure of atmospheric pressure Vertical structure of atmospheric pressure & temperature & temperature

3.3. Types of weather & climate in the Types of weather & climate in the atmosphereatmosphere

Solar Energy as RadiationSolar Energy as Radiation

Figure 1.1Figure 1.1

Nearly 150 million kilometers separate the sun and earth, yet solar Nearly 150 million kilometers separate the sun and earth, yet solar radiation drives earth's weather.radiation drives earth's weather.

Earth's AtmosphereEarth's Atmosphere

99% of atmospheric gases, including water vapor, extend only 30 99% of atmospheric gases, including water vapor, extend only 30 kilometer (km) above earth's surface.kilometer (km) above earth's surface.

Most of our weather, however, occurs within the first 10 to 15 km.Most of our weather, however, occurs within the first 10 to 15 km.

Figure 1.2Figure 1.2

Atmospheric GasesAtmospheric Gases

Figure 1.3Figure 1.3

Nitrogen, oxygen, Nitrogen, oxygen, argon, water vapor, argon, water vapor, carbon dioxide, and carbon dioxide, and most other gases most other gases are invisible.are invisible.

Clouds are not gas, Clouds are not gas, but condensed but condensed vapor in the form of vapor in the form of liquid droplets.liquid droplets.

Ground based Ground based smog, which is smog, which is visible, contains visible, contains reactants of reactants of nitrogen and ozone.nitrogen and ozone.

Variable & Increasing GasesVariable & Increasing Gases

Figure 1.4Figure 1.4Figure 1.5Figure 1.5

Nitrogen and oxygen concentrations experience little change, Nitrogen and oxygen concentrations experience little change, but carbon dioxide, methane, nitrous oxides, and but carbon dioxide, methane, nitrous oxides, and chlorofluorocarbons are greenhouse gases experiencing chlorofluorocarbons are greenhouse gases experiencing discernable increases in concentration.discernable increases in concentration.

Aerosols & PollutantsAerosols & Pollutants

Human and Human and natural activities natural activities displace tiny soil, displace tiny soil, salt, and ash salt, and ash particles as particles as suspended suspended aerosols, as well aerosols, as well as sulfur and as sulfur and nitrogen oxides, nitrogen oxides, and and hydrocarbons as hydrocarbons as pollutants.pollutants.

Figure 1.6Figure 1.6

Pressure & DensityPressure & Density

Figure 1.7Figure 1.7

Gravity pulls gases Gravity pulls gases toward earth's toward earth's surface, and the surface, and the whole column of whole column of gases weighs 14.7 gases weighs 14.7 psi at sea level, a psi at sea level, a pressure of 1013.25 pressure of 1013.25 mb or 29.92 in.Hg.mb or 29.92 in.Hg.

Vertical Pressure ProfileVertical Pressure Profile

Pressure increases at a Pressure increases at a curved rate curved rate proportional to altitude proportional to altitude squared, but near the squared, but near the surface a linear surface a linear estimate of 10 mb per estimate of 10 mb per 100 meters works well.100 meters works well.

Figure 1.8Figure 1.8

Atmospheric LayersAtmospheric Layers

Figure 1.9Figure 1.9

8 layers are defined by constant 8 layers are defined by constant trends in average air trends in average air temperature (which changes temperature (which changes with pressure and radiation), with pressure and radiation), where the outer exosphere is not where the outer exosphere is not shown.shown.

Atmospheric Mixture & ChargeAtmospheric Mixture & Charge

Additional layers Additional layers include: include:

a) the homosphere a) the homosphere with 78% nitrogen with 78% nitrogen and 21% oxygen and 21% oxygen

b) the poorly b) the poorly mixed mixed heterosphereheterosphere c) the electrically c) the electrically charged charged ionisphereionisphere

Figure 1.10Figure 1.10

Radio Wave PropagationRadio Wave Propagation

Figure 1.11Figure 1.11

AM radio waves are long enough to interfere with ions in the sun-AM radio waves are long enough to interfere with ions in the sun-charged D layer, but at night the D layer is weak and the AM signal charged D layer, but at night the D layer is weak and the AM signal propagates further, requiring stations use less power.propagates further, requiring stations use less power.

Weather & ClimateWeather & Climate

Weather is comprised of Weather is comprised of measured:measured: a) air temperature a) air temperature b) air pressure b) air pressure c) humidity c) humidity d) clouds d) clouds e) precipitation e) precipitation f) visibilityf) visibilityg) windg) wind

Climate represents long-term Climate represents long-term (e.g. 30 yr) averages of weather.(e.g. 30 yr) averages of weather.

Satellite InstrumentsSatellite Instruments

Meteorologists may Meteorologists may study larger weather study larger weather patterns with space patterns with space borne instruments, borne instruments, while ground-based while ground-based tools often measure a tools often measure a single point.single point.

Figure 1.12Figure 1.12

Surface Weather MapSurface Weather Map

Figure 1.13Figure 1.13

Meteorologists Meteorologists generate diagrams generate diagrams of observed of observed weather from weather from ground-based ground-based instruments.instruments.

This surface map This surface map overlaps in time overlaps in time with the previous with the previous satellite image.satellite image.

Impacts of Weather 1/5Impacts of Weather 1/5

Figure 1.14Figure 1.14

Impacts of Weather 2/5Impacts of Weather 2/5

Figure 1.15Figure 1.15

Impacts of Weather 3/5Impacts of Weather 3/5

Figure 1.16Figure 1.16

Impacts of Weather 4/5Impacts of Weather 4/5

Figure 1.17Figure 1.17

Impacts of Weather 5/5Impacts of Weather 5/5

Figure 1.18Figure 1.18